TIPS FOR ENERGY ENERGY SAVING SAVING IN INDUSTRIAL EQUIPMENTS The industrial sector alone accounts for about 50% of the commercial energy. It uses both, the thermal and electrical energy in various equipments like boilers, compressors, furnaces, diesel generating engines, motors, pumps, refrigeration refrigeration etc. Here are tips for energy saving through these equipments. Electrical Energy – General
The industrial sector consumes about 33 per cent of the total electrical energy consumed in the country. Tips for electrical energy saving:
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Impro Improve ve power facto factorr by installi installing ng capacito capacitors rs to reduce reduce KVA KVA demand demand charges charges and also line losses within plant.
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Impro Improvem vement ent of powe powerr factor factor from from 0.! 0.! to 0."# 0."# will will give give $$.!% $$.!% redu reducti ction on of pea& KVA KVA and '$.#% reduction in pea& losses. This corresponds to $(.!% reduction in average losses for a load factor of 0..
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Avoid void repeate repeated d rewindin rewinding g of motors motors.. )bserva )bservatio tions ns show show that rewoun rewound d motors motors practically have an efficiency loss of upto !%. This is mainly due to increase in no load load loss losses es.. *ence *ence use use such such rewo rewound und moto motors rs on low low duty duty cycl cyclee applications only.
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+se +se of vari variab able le fre, fre,ue uenc ncy y driv drives es-- slip slip powe powerr reco recove very ry syst system emss and and flui fluid d couplings for variable speed applications such as fans- pumps etc. helps in minimiing consumption.
Compressed air:
/ompressed air is used in almost all types of industries and accounts for a maor share of 1lectricity used in some of the plants. It is utilied for a variety of end uses such as pneumatic tools and e,uipment- instrumentation- conveying- etc. and is preferred in Industries because of its convenience and safety. 2ormally- the compressed air factor is an overloo&ed area in most of the industries- though it is a costly source of power- about to $0 times the cost of electricity. 4iven this economics- better maintenance practices and elimination of wastage would help in improving the performance of compressed air systems.
Tips for energy saving:
• /ompressed air is very energy intensive. )nly !% of electrical energy is converted to useful energy. +se of compressed air for cleaning is rarely ustified. • 1nsure low temperature of inlet air. Increase in inlet air temperature by 35/ increases power consumption by $%. • It should be e6amined whether air at lower pressure can be used in the process. 7eduction in discharge pressure by $0% saves energy consumption upto !%. • A lea&age from a 89 diameter hole from a compressed air line wor&ing at a pressure of &g:cm' can drain almost 7s. '!00 per day. • Air output of compressors per unit of electricity input must be measured at regular intervals. 1fficiency of compressors tends to deteriorate with time. Cooling towers:
A cooling tower is a specialied heat e6changer in which two fluids ;air and water< are brought into direct contact with each other to effect the transfer of heat. In a spray filled towers- this is accomplished by spraying a flowing mass of water into a rain = li&e patternthrough which an upward moving mass flow of cool air is induced by the action of a fan. There are two basic types of cooling towers- direct ;or open< and indirect ;or closed<. Tips for energy saving:
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7eplacement of inefficient aluminum or fabricated steel fans by moulded >7? fans with aerofoil designs results in electricity savings in the range of $!=(0%.
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A study on a typical '0 ft. diameter fan revealed that replacing wooden blade drift eliminators with newly developed cellular ?V/ drift eliminators reduces the drift losses from 0.0$=0.0'% with a fan power energy saving of $0%.
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Install automatic on-off switching of cooling tower fans and save upto (0% on electricity costs.
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+se of ?V/ fills in place of wooden bars results in a saving in pumping power of upto '0%.
Electric motors:
The electric motors are used to provide motive power to e,uipment such as compressors- pumps- blowers- etc. It is important that the industrial users define their need accurately to enable proper selection of a motor for a particular application. )f the total electricity consumed in the industrial sector- electric motors account for appro6imately 0%. The motors are classified under @/ ;direct current<- A/ ;alternating current< synchronous- and A/ induction ;s,uirrel cage or wound rotor type< types. The A/ induction is additionally distinguished as single or polyphase. ost of the power consumed by motors in the industry is accounted for by polyphase ;three=phase< A/ induction motors. )f the three=phase induction motors- the s,uirrel cage motor is most popularly used because of its relatively low capital and maintenance costs- and rugged design. Tips for energy saving:
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The motors should be energy efficient.
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/onvert delta to star connection for lightly loaded motors.
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Install soft start=cum=energy saver for lightly loaded motors.
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In case of centrifugal=blower pump- install variable voltage fre,uency ;VVV>< drives for speed control of motors.
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Install multi speed motor.
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)ptimie operating voltage level of motor for lightly loaded motors
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7eplace eddy current controls with variable fre,uency drives for varying speed driven e,uipmentB
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?rovide interloc& for electric motor to avoid idle running
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7eplace motor generating sets with thyristor drives.
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Avoid fre,uent rewinding of motors. 4reater the number of rewind- lesser the efficiency.
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/arry out preventive maintenance and condition monitoring schedule regularly.
Advantages of Energy Efficient Motors
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7educed operating costs
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Cess heat losses
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16tended winding lifespan
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16tended lubricating grease service life
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Cower noise levels than other motors
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7educed energy costs. The higher purchase price investment pays off.
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7educe emission of /)' and 2)6 greenhouse gasses from power stations for positive environmental effect.
Lighting:
A lumen is the measurement of light output from a lamp- often called a tube or a bulb. All lamps are rated in lumens. >or e6ample- a $00=D incandescent lamp produces about $!0 lumens. The distribution of light on a horiontal surface is called its illumination- which is measured in foot=candles or lu6. A foot=candle of illumination is a lumen of light distributed over one=s,uare=foot ;0.0" m'< area. Another lighting term is efficacy- which is the ratio of light output from a lamp to the electric power it consumes and is measured in C?D ;lumens per watt<. Cighting uses can be divided into three categoriesE ambient- tas&- and accent. Ambient lighting provides security and safety- as well as general illumination for performing daily activities. The goal of tas& lighting is to provide enough illumination so that tas&s can be completed accurately. The idea here is not to illuminate the entire area. Accent lighting illuminates walls to blend more closely with naturally bright areas li&e ceilings and windows. Tips for energy saving: • +se of electronic ballast in place of conventional cho&e saves energy upto '0%.
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+se of />C lamp in place of 4CF lamp can save energy upto 0%.
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/lean the lamps and fi6tures regularly. Illumination levels fall by '0=30% due to collection of dust.
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+se of 3#D tube light instead of (0 D tube light saves electricity by to $0%.
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+se of sodium vapour lamps for area lighting in place of mercury vapour lamps saves electricity upto (0%.
PumpsE
ost of the industrial processes in and out of plants involve transportation of fluids and the pump is the only mechanical means available to facilitate this transportation. Dor& has to be done by a prime mover in order to enable the pump to discharge its functions- because the pump is incapable of transporting the fluid on its own. The prime mover can either be an electric motor- a diesel engine- on a steam:gas turbine. All prime movers consume energy- either in the form of electric power or precious petroleum products li&e diesel- oil or gas- to impart wor&ing capacity to the pump. Tips for energy savingE • Felect a pump of the right capacity in accordance with the re,uirement. Improper selection of pumps can lead to large wastage of energy. A pump with !% efficiency at rated flow may have only #!% efficiency at half the flow. •
atching of the motor with the appropriate=sied pump.
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+se of throttling valves instead of variable speed drives to change flow of fluids is a wasteful practice. Throttling can cause wastage of power to the tune of !0 to #0%. It is advisable to use a number of pumps in series and parallel to cope with variations in operating conditions by switching on or off pumps rather than running one large pump with partial load.
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Void valves in the pipe line throttle wastes energy. A positive displacement pump with variable speed drive is recommended.
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?roper installation of the pump system- including shaft alignment- coupling of motor and pump is a must. @rive transmission between pumps and motors is very important. Coose belts can cause energy loss upto $ !='0%.
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odern synthetic flat belts in place of conventional V=belts can save !% to $0% of energy. ?roperly organied maintenance is very important. 1fficiency of worn out pumps can drop by $0=$!% unless maintained properly.
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Refrigeration and Air-Conditioning:
7efrigeration is the process of removing heat at a low temperature level and reecting it at a relatively higher temperature level. 7efrigeration is accomplished by various methodssuch as the vapour compression system- absorption system- and steam et refrigeration cycle. The most commonly used systems are the vapour compression and absorption
systems. >urther- even out of above two- the vapour compression system is more widely used. The items re,uired for the ma&e=up of a complete refrigeration and air=conditioning system are refrigerating e,uipment- fans- pumps- cooling towers- filters- air=handling units- and ducting. @epending upon the process- all or some of the items mentioned may be re,uired. Tips for energy saving:
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/lose doors and windows while running the air conditioning. @onGt use a whole house fan or window fan while the air conditioner is on- but do use a ceiling fan.
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+se of double doors- automatic door closers- air curtains- double glaed windows polyester sun films etc. reduces heat ingress and air=conditioning load of buildings.
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aintain condensers for proper heat e6change. A !5/ decrease in evaporator temperature increases the specific power consumption by $!%.
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+tiliation of air=conditioned:refrigerated space should be e6amined and efforts made to reduce cooling load as far as possible. +tilie waste heat of e6cess steam or flue gases to change over from gas compression systems to absorption chilling systems and save energy costs in the range of !0=0%.
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The compressor of the central air conditioner should be located in a cool- shaded place outside.
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Fpecific power consumption of compressors should be measured at regular intervals. The most efficient compressors to be used for continuous duty and others on standby.
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The air conditioning unit must be inspectedH cleaned and tuned by a professional every two to three years to &eeps it going longer and to using less electricity. If the refrigerant needs to be recharged- ma&e sure it is done correctly. If it is overcharged- it would reduce operating efficiency and could damage the unit. If it is undercharged it would also use energy less efficiently.
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The duct system should be properly sealed. This could save $0 per cent to $! per cent of the electricity into air conditioner.
Thermal Energy – General
The coal- lignite and petroleum products li&e diesel furnace oil- C?4- natural gas are the sources of thermal energy and their savings is very imperative as coal and lignite
deposits are depleting year after year- petroleum products are eating away foreign e6change. Tips for energy saving:
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+nderta&e regular energy audits.
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?lug all oil lea&age as lea&age of one drop of oil per second amounts to a loss of over '000 liters:year.
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>ilter oil in stages. Impurities in oil affect combustion.
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?re=heat oil. >or proper combustion- oil should be at right viscosity at the burner tip. ?rovide ade,uate ?re=heat capacity.
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Incomplete combustion leads to wastage of fuel. )bserve the color of smo&e emitted from chimney. lac& smo&e indicates improper combustion and fuel wastage. Dhite smo&e indicates e6cess air and hence loss of heat. *ay brown smo&e indicates proper combustion. +se of low air pressure Jfilm burnersJ helps save oil upto $!% in furnaces. The maintenance in plant should follow the Jero lea&J philosophy- particularly in the areas of steam and utilities so that loss of energy could be totally eliminated.
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oilers:
oilers are used in various industrial units to convey heat for different process applications. Fteam is commonly used as the heating medium mainly due to two reasonsE one =it is generated from water which is usually availableH and two=it is able to store a large ,uantity of heat at a temperature which can be conveniently used. Various types of fuels- namelyH coal- oil- gas- biomass- etc. are used for steam generation in boilers depending on the availability of fuel and cost economics prevailing in the plant. Fome of the boilers even use waste ;generally low calorific value fuels< as fuel. >or e6ample paper industries use blac& li,uor generated within the plant as fuel. oilers can be categoried into different types depending on water:flue gas passage in the boiler- fuel usage- and pressure generation. The types of b oilers vary with respect to the re,uirement of the plant. Dhatever may be the type of boiler used- the motive of the industry should be to generate the re,uired ,uantity and ,uality of steam at minimum possible costs. This can only be achieved by reducing the various avoidable heat losses occurring within the boiler system- thus improving the efficiency of the same. @ifferent boilers will have different efficiency levels depending on the fuel type as shown in the table on ne6t page.
Tips for energy saving:
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All possible attention= should be paid to control e6cess air by monitoring o6ygen level in flue gas and also by visual inspection of flame color.
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7emove soot deposits when flue gas temperature rises (05/ above the normal. A coating of 3mm thic& soot on the heat transfer surface can cause an increase in fuel consumption of as much as '.!%.
• Foot blowers can always be maintained in perfect wor&ing condition so that their regular and periodic use does not suffer. • 7ecover heat from steam condensate. >or every #5/ rise in boiler feed water temperature through condensate return- there is $% saving in fuel. • Improve boiler efficiency. oilers should be monitored for flue gas losses- radiation losses- incomplete combustion- blow down losses- e6cess air etc. ?roper control can decrease the consumption upto '0%. • +se only treated water in boilers. A scale formation of $ mm thic&ness on the waterside increases fuel consumption by !=%. • Ftop steam lea&age. Fteam lea&age from a 3 mm=diameter hole on a pipeline carrying steam at &g:cm' would waste 3' &l of fuel oil per year amounting to a loss of 7s. 3 la&h. • aintain steam pipe insulation. It has been estimated that a bare steam pipe- $!0 mm in diameter and $00m in length- carrying saturated steam at &g:cm' would waste '! &l of furnace oil in a year amounting to an annual loss of 7s. '.! la&h. Thermal efficiency le!els oiler type anually=fired Fto&er=fired /oal=fired )il and as = fired u to '0 tonnes:hour Above '0 tonnes:hour >luidied=bed combustion Daste=heat ?ulveried=fuel=fired
Variations (0=#0 #!=0 !!=#0 0=0 0=! !=0 !!=! 0=!
"iesel generating sets:
Dith the gap between the demand and supply of electric power widening- the role of diesel generating sets in the Indian industry cannot be overemphasied. @epending on the type of industry- its sitting- and the magnitude of the connected load- @4 sets are employed in various modes li&eE the standby mode to meet a part or the full re,uirement of the plant in case of power failuresH the pea&=load mode to meet the re,uirement during pea& demand- thereby reducing the ma6imum demandH the base=load mode- where a part or whole of the plantGs re,uirement is met on a continuous basisH and the total energy mode- where it not only supplies the total power re,uired but also meets the heating and cooling re,uirements of the plant by utiliing the waste heat from the @4 set e6haust in an integrated system. Tips for energy saving: • aintain diesel engines regularly. • A poorly maintained inection pump increases fuel consumption by (gm:&Dh. • A faulty nole increases fuel consumption by 'gm:&Dh. • loc&ed filters increase fuel consumption by 'gm:&Dh. • A continuously running @4 set can generate 0.! ton:hr of steam at $0 to $' bars from the residual heat of the engine e6haust per D of the generator capacity. • easure fuel consumption per KD* of electricity generated regularly. Ta&e corrective action in case this shows a rising trend. Furnace - Tips for energy saving:
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7ecover and utilie waste heat from furnace flue gases for preheating of combustion air. 1very '$5/ rise in combustion air temperature results in $% fuel oil savings. /ontrol e6cess air in furnaces. A $0% drop in e6cess air amounts to $% saving of fuel in furnaces. >or an annual consumption of 3000 KC of furnace oil means a saving of 7s 3 la&hs- ;cost of furnace oil=7s. $0 per liter<.
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7educe heat losses through furnace openings. )bservations show that a furnace operating at a temperature of $0005/ having an open door ;$!00mm !0mm< results in a fuel loss of $0 lit:hr. >or a (000 hrs furnace operation- this translates into a loss of appro6. 7s. ( la&hs per year.
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Improve insulation if the surface temperature e6ceeds '05/ above ambient. Ftudies have revealed that heat loss form a furnace wall $$!mm thic& at #!05/ amounting to '#!0 &cal:m':hr can be cut down to !0 &cal:m'hr by using #! mm thic& insulation on the $$! mm wall.
